Combination of SERS with Principle Component Analysis (PCA) allows segregating different antigen-antibody interactions into separate clusters, which subsequently makes it possible to differentiate among ABO blood groups. Distinctive spectral changes among all types of the studied blood groups were found for mixtures of red blood cells (RBCs) with the A or B antibody. For PCA analysis, all the spectral data were divided into two main groups based on the type of antibody. The obtained PC scores in the area marking antigen–antibody interactions (1311–1345 cm-1) allow differentiation within blood groups with accuracy from 96% to 98%.

Variations of the band intensity of RBCs antigen (B blood group)–antibody solution (1 : 1 ratio) depending on the added B antibody concentration. The most pronounced bands coming from globin vibrations in the antigen–antibody complex are marked by asterisks.